1. Field of the Invention
The present invention provides a testing device; and more particularly, to an impact testing device.
2. Descriptions of the Related Art
Impacting testing devices are used to measure the reliability of products in the following principle: a regular or irregular impacting force is generated by an impact testing device to impact an object under testing (i.e., a product). Then, through accumulative impact fatigue over a long period of time, potential defects in the object undergoing testing can be measured to evaluate the internal components and structures or the protection level of outer packages as a basis of improving reliability in use and product quality.
In the conventional impact testing device, the object undergoing testing is placed on a platform of the impact testing device and, then, by means of at least one impact assembly disposed under the platform, an impact test is executed on the platform and the object undergoing testing to measure the potential defects after impact. Although this approach of using at least one impact assembly to impact the object undergoing testing from bottom to top can provide related impact testing data, the impact force generated by the at least one impact assembly is imposed on both the platform and the object undergoing testing simultaneously during the impact process. Therefore, a part of the impact force (or even most part of the impact force) is absorbed by the platform and consumed by actions unrelated to the impact test.
On the other hand, according to Newton's Third Law of Motion, when two objects interact with each other, the forces applied to each other have the same magnitude and opposite directions. For this reason, Newton's Third Law of Motion is also called “Law of Acting Force and Reacting Force”. According to this law, when an impact test is executed by at least one impact assembly to generate an impact force to the platform, a reacting force will also be generated to the at least one impact assembly. Consequently, because both the platform and the at least one impact assembly belong to the impact testing device and their spatial positions are associated with each other, a reacting force will be generated to the at least one impact assembly according to Newton's Third Law of Motion when the impact force is applied by the at least one impact assembly to the object undergoing testing. The reacting force will indirectly cause impact to the platform and the object undergoing testing to affect the final testing results. This effect is particularly significant when the at least one impact assembly is a single impact assembly and comprises a plurality of impact hammers.
The following case in which a single impact assembly comprises two impact hammers (i.e., a first impact hammer and a second impact hammer) disposed opposite each other and the two impact hammers impact the platform obliquely at an angle of 45° respectively will be used as an example. If the two impact hammers impact the platform in sequence, a reacting force generated according to Newton's Third Law of Motion will be applied to the second impact hammer after impact from the first impact hammer has been completed but before the impact from the second impact hammer begins. This reacting force will affect the impact force imposed by the second impact hammer on the platform and cause measurement errors.
Errors may also be caused if there is insufficient time between the impact of the first impact hammer and the second impact for the platform to restore its initial stationary position. In this case, the minor displacement of the platform may also affect the testing results.
As can be known from the above descriptions, although the conventional impacttesting devices can measure potential defects after the object undergoing testing is impacted, numerous variables or instable factors still exist in the testing process. As a result, it is difficult to achieve precise control and accurate results.
Additionally, the stress produced at the instant of impact by the impact hammers excites a natural response in the object undergoing testing. When the object undergoing testing is a device or a system comprised of a plurality of elements, the stress produced at the instant of impact by the impact hammers excites a natural response of each of the elements. As has been found through research, interferences between the natural responses between individual elements are actually the most prominent factor that causes damage to the elements or the system.
In other words, because conventional impact testing devices cannot accurately control the impacting on the object undergoing testing, it is difficult to establish a shock response spectrum (SRS) by measuring interferences between the natural responses of the individual elements. It is also difficult to accurately determine the reliability and service life of the object undergoing testing.
Accordingly, it is important to provide an impact testing platform which, during impact testing, can effectively eliminate influences of the aforesaid acting force and reacting force and minimize the displacement of the platform to make the impact testing results accurate.